Cold War Sites

GPO PR1 Protected Repeater Station

 Created 21-10-2001   Last update 03-08-2014

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If you can improve on the narrative that accompanies the following photos then please email me.

continuity control set

036 - HV switch room. The continuity control panel for the continuity set (photo 008). The 3 phase output had to be synchronised with the incoming supply phases before it was switched in. There are tales of someone getting one 180 degrees out of phase and the set leaping from the floor when it was switched in!

HV switch gear main switch


043 - HV switch gear main switch


transformer room doors

041 - Steel transformer room doors. One the left (top) is the CO2 dump switch. If a fire occurs in this room the switch can be thrown from the outside and carbon dioxide will fill the room suppressing the fire. The lower switch is for tripping the breakers to turn the power off.

The transformers that used to be in here were oil filled, similar to those you see in small sub stations every few streets around your home. There was a small retaining wall beneath the doors and a shingle bed on the floor, in case of oil spillage.


007 - Transformers. These step down the AC voltage from the generator to something more usable such as 415 volts 3 phase.

Pump starter switches


028 - Pump starter switches - for pumps doing what?


NEW - 03-08-2014

I think the pumps you have displayed on photograph 028 were to raise diesel from the underground tanks to the header tanks mounted high above the alternators. You can see them on photograph 001, top left. I remember similar tanks in the old Central Exchange Power Room at Newcastle upon Tyne when I was an apprentice. I also had to prime the oldest generator set with one of the large wooden handled pumps you have on photograph 005. Great pictures.

Terry Kirkup, ex-GPO Engineer

Escape shaft 


035 - Escape shaft leading to the ground floor.


Ventilation system 

026 - Ventilation system

Ventilation 'T' splitter

018 - Ventilation 'T' splitter with measuring and recording instruments.


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